Updated

It is being described as one of the biggest heists in archaeological history.

A priceless collection of 7,700 gold, silver and bronze coins from ancient times -- known as the Treasure of Benghazi -- was stolen when a gang drilled through the concrete ceiling of an underground vault in the Libyan city earlier this year.

An expert described it last week as "one of the greatest thefts in archaeological history," with many of the items dating from the time of Alexander the Great.

It is impossible to give a value for the hoard but a single ancient Greek coin from Carthage was sold this month for the record price of $431,000 at auction in Paris, The (London) Sunday Times reported.

Metal storage cupboards at the National Commercial Bank of Benghazi had been smashed open and the red wax seals on the wooden trunks housing the collection were broken.

The gang had concentrated on the ancient treasures, leaving items of lesser value untouched.

It may have been an inside job. The theft appears to have been carried out by people who knew what they were looking for.

The Benghazi raid had occurred soon after an arson attack on the bank. At first this was believed to have been part of the uprising against fallen dictator Muammar Qaddafi, but it may have been linked to the well organized robbery, which took place in May.

At the time the city was battling for survival against Qaddafi's troops. Benghazi had been the first city to fall to the rebels but still came under sustained attack from Qaddafi loyalists.

As well as the coins, the hoard of antiquities included jewelry, medallions, bracelets, anklets, necklaces, earrings, rings and gold armbands. About 50 small monuments and figurines of bronze, glass and ivory are missing and also a small cache of precious stones.

Hafed Walda, a Libyan archaeologist based at King's College London, said the robbery bore the hallmarks of a professional heist: "It may have been an inside job. It appears to have been carried out by people who knew what they were looking for."

The theft has gone unreported until now. Fadel Ali Mohammed, the new Libyan minister for antiquities, first raised the alarm with UNESCO, the United Nations heritage watchdog, in July.

There has been speculation that Libya's Transitional National Council, then based in Benghazi, was not keen to publicize the robbery for fear of negative publicity.

Interpol has been alerted but the trail has gone cold and archaeologists fear it could be difficult to return the items once they are moved outside the country.

Serenella Ensoli, an Italian archaeologist at the Second University of Naples and a specialist in Libyan antiquities, described the robbery as "a very serious loss for archaeological heritage on a global scale."

Ensoli said the treasure's value was "inestimable" because the historical value of the items made them irreplaceable.

"The collection is not well studied, it is a huge loss for Libya's heritage," she said.